Oct. 1, 2010 -- Some cancer survivors refer to the mental haze they experience as "chemo brain" or "chemo fog," although this mental fuzziness may occur after other cancer treatments as well -- and sometimes even precedes treatment.

Now a new study shows that people with a history of cancer are 40% more likely to experience memory problems and trouble concentrating when compared to people who have no history of cancer. The findings are slated to be presented at the 3rd American Association for Cancer Research Conference on the Science of Cancer Health Disparities in Miami.

"For some people, it is very subtle and mild, but in others, it can be more severe and interfere with their function," says study researcher Pascal Jean-Pierre, PhD, MPH, an assistant professor of pediatrics at the University of Miami Miller School of Medicine. "People complain of problems focusing, paying attention, remembering, and these issues are more apparent during multitasking."

What's more, these memory problems "are lasting and enduring. Some people still report memory issues 10 years after cancer therapy," he tells WebMD.

Whether it is the cancer itself, its treatment, or even the anxiety that comes with a cancer diagnosis that is causing the memory issues is not fully understood.

"There is evidence that the tumor biology itself and/or the treatment the patients received can cause the problem," Jean-Pierre says.

The new findings are based on data from the National Health and Nutrition Examination Survey of more than 9,800 people aged 40 and older. Of these, 1,305 people said they either currently had cancer or had a history of cancer. Fourteen percent of people with cancer had memory issues, compared with 8% of survey responders without any cancer. When compared to people in the survey without a history of cancer, people with cancer were 40% more likely to have memory issues that limited their daily activities.

More and more people are surviving cancer today due to better detection and treatment options, so quality-of-life issues such as cancer-related memory problems need to be on doctors' radar screens and taken seriously, Jean-Pierre says.

"It should be assessed more systematically in practice, and patients should report any symptoms or concerns with their memory to their doctors," he says. "It could impact your daily functioning, and if you are not remembering your daily treatment regimen, you can run into trouble." Some cancer survivors may need to take daily medication to keep their cancer at bay.

Treatments aimed at improving "chemo brain" such as medications or behavioral interventions are being studied.

"Keeping physically active may also help," he says. "People do improve, but they don't return to baseline or their pre-cancer level."

This is an all-too familiar scenario for breast and bone cancer survivor Andrea Mulrain, a 45-year-old researcher in Seattle. "I wasn't so much forgetting things, but I was in a mental fog and not able to clearly focus," she tells WebMD. She is not sure how long it lasted, but she suspects this haze lingered for two years after she underwent chemotherapy for breast cancer.

"I tried to stay engaged and organized to help counteract it; exercise seemed to help, too," she says.

The new study "brings attention to a very important cancer survivorship issue," says Jeffrey S. Wefel, PhD, an assistant professor of neuro-oncology at the University of Texas M.D. Anderson Cancer Center in Houston.

"If you are having these symptoms, bring them to your physician's attention," he says. Treatment may help.

Many studies on this phenomenon have been of breast cancer survivors, he tells WebMD. "There has been a subset of women with breast cancer who exhibit memory impairments at diagnosis, but before treatment so there is some suggestion that the cancer itself may cause changes in the biological milieu and cause cognitive problems, but the jury is still out as there is no clear answer to why this occurs."